.flow-twill {
    padding-right: 30%;
    height: calc(1.4142 * 20px);
    background: repeating-linear-gradient(45deg, teal, teal 10px, transparent 11px, transparent 19px, teal 20px);
    background-clip: content-box;
    animation: twill 1s linear infinite;
    position: relative;
}
.flow-twill::before {
    content: '';
    position: absolute;
    width: 100%; height: 100%;
    background: linear-gradient(rgba(0,0,0,.5), hsla(0,0%,100%,.5), rgba(0,0,0,.5));
}
@keyframes twill {
    from {
        background-position: 0 0;
    }
    to {
        background-position: 0 calc(-1 * 1.4142 * 40px);
    }
}